The invention generally relates to sewage treatment apparatus and, more particularly, to sewage treatment apparatus for use on vessels, such as marine vessels.
Sewage or waste water treatment plants are generally known. It is also known to provide such apparatus on marine vessels. In marine applications, the capacity of the treatment plant is typically sized according to the number of persons carried by the vessel, whereby, for example, sewage treatment plants on passenger ships and freighters are of a totally different size category.
In the following both the terms sewage and waste water are used. These terms comprise waste from sanitary installations, such as toilets, urinals, wash basins, hospitals, and sick bays, as well as kitchens, food stuff treatment facilities, and the like. Other terms used in this connection are black water and grey water, as are generally understood in the art.
A typical apparatus for sewage treatment comprises as basic components an aeration chamber, a settling chamber, and a disinfection chamber for the sewage. In the aeration chamber the organic components of the sewage are transformed by means of bacteria into carbon dioxide and water. The air necessary for the process is usually produced by blowers. From the aeration chamber, the treated waste water is led to the settling chamber, from where the separated sediment is returned back to the aeration chamber for further disintegration. From the settling chamber, the cleared water is led to the disinfection chamber, where disinfection is carried out either chemically and/or by UV-light or UV-radiation. From the disinfection chamber, the cleaned water can be emptied into the sea, a receiving facility on land, such as a sewer network, or into a storage container at some other location aboard the vessel.
In known waste water treatment plants intended for use on ships, the aeration chamber, settling chamber, and disinfection chamber form a separate entity, wherein short transfer connections are installed between the chambers, and whereby the fluid is arranged to flow from one chamber to another by way of overflow. The treatment plant is usually preceded by a collecting container which has the function of guaranteeing a stable load for the treatment plant at all hours of the day. A storage container is often arranged after the treatment plant and clearly separated from the same, having the function of storing the waste water cleaned aboard the vessel at times when it cannot be discharged into the sea due, for example, to different regulations, such as into a harbor basin when the vessel is in a harbor.
In known apparatus the storage container is always a container situated apart form the treatment plant and often arranged at the bottom of the hull, whereas the treatment plant is placed in the machine room, and therefore the transfer connections from the treatment plant to the storage container are long, thereby increasing the possibility of leaks in the connecting piping. Furthermore, in conventional apparatus, each system needs its own pumping station and level metering system, including control automation.
In view of the foregoing, an apparatus for the treatment of sewage is described herein which provides for an efficient and multifunctional sewage treatment process by simple means, while avoiding the aforementioned disadvantages.
In this regard, the sewage treatment plant and the storage container intended for use on a ship are provided, as much as possible, as an integrated structure, whereby the means necessary for the transfer connections and the control of the same can be minimized and whereby an efficient as possible interaction can be achieved between the different components of the apparatus. Accordingly, the aeration chamber, the settling chamber, the disinfection chamber, and the storage container are integrated in the same structure, whereby at least the level metering system, the pumping station, and the control center can be combined into one unit, i.e. having the process and its control monitored from a central arrangement. The disinfection chamber and the storage container can be arranged as separate units and provided with surface level sensors connected to a control center. This provides for a controlled temporary storage stage when direct discharge of treated waste is not possible.
The storage container can also be arranged directly as a fixed part of the structure of the treatment plant, whereby the disinfection chamber, for example, may be expanded from being only a disinfection chamber into a multifunctional combined disinfection chamber-storage container. The combined control of this arrangement may advantageously be provided with surface level sensors connected to a control center.
At the aeration stage preferably two (i.e. a first and a second) aeration chambers are used in order to optimize the aeration stage.
To provide for alternative ways of treating sewage, the first aeration chamber and the storage container may be provided with sewage supply pipes connected to the source of sewage. This means, for example, that the sewage treatment process may also temporarily be by-passed, such as during annual maintenance, whereby the sewage can be collected directly in the storage container, from where the sewage can be returned to the aeration chamber for treatment to be carried out later. The treatment process can thus be finished after annual maintenance or some other interruption.
It has also shown to be advantageous that the sewage supply pipes connected to the first aeration chamber and the storage container be further connected to an ejector device when the apparatus is employed in connection with a vacuum waste system.
The above mentioned arrangements further provide for both the aeration chamber and the storage container to function directly as a collecting container for sewage.
The disinfection chamber and the storage container may be advantageously provided with a common pump means connected to the control center in order to further centralize the arrangement.
The disinfection chamber may be advantageously provided with a disinfection system comprising a disinfectant container and a dosage pump connected to the control center as noted above.
The integrated structure of the device according to the invention provides for connecting all the operating means to the central control center.
Other features and advantages are inherent in the embodiments claimed and disclosed, or will become apparent to those skilled in the art from the following detailed description and accompanying drawings.